In recent decades land use and land cover change (LULCC) has occurred throughout the Intermountain West. The Crown of the Continent Ecosystem (CCE) extends along the Rocky Mountains adjacent to the Canada-U.S. International border. In the U.S. portion of the CCE, located in northwestern Montana, development has increased since the 1990s, largely because of urban to rural migration. The CCE has become an amenity-based destination, which in turn is likely to threaten its terrestrial and aquatic ecological diversity (Quinn and Broberg 2007). Specifically, development pressures on private lands surrounding federally protected lands, are intensifying and thus threatening core habitat of native species and connectivity of forested areas. By characterizing the spatial and temporal patterns of LULCC, we can better understand landscape-scale changes influenced by human-environment interactions. Using National Land Cover Database (NLCD) products, I identified areas that have experienced land cover change for three time periods: 1992-2001, 2001-2006, and 2006-2011. Additionally, I used case studies to further investigate LULCC in the study area. The findings suggest that the highest rates of development in proximity to Glacier National Park were dependent on existing urban land cover, meaning existing roadway infrastructure and established urban areas saw the greatest urban development. Additionally, communities adjacent to Glacier National Park were hotspots for urban development. Based on the results, areas in proximity to federally protected lands are likely to experience continued urban intensification over the next few decades. / Master of Science

L'isthme de Panama se situe en bordure SW de la plaque Caraïbe, à la jonction de trois plaques lithosphériques: les plaques Amérique du Sud, Nazca et Cocos. Cet isthme est constitué de deux arcs volcaniques formant l'Amérique Centrale. Leurs présences reflètent une histoire complexe de convergence, en subduction. L'événement majeur de cette région correspond à la collision de l'Amérique Centrale contre l'Amérique du Sud entre 12-25 Ma. L'objectif de cette thèse est de documenter les déformations avant, pendant et après le processus d'accrétion continentale. Le but est de mieux comprendre comment un arc volcanique s'accrète sur une marge continentale pour reconstruire l'histoire géodynamique de cette région de 70 Ma jusqu'à nos jours. Cette thèse combine: - une étude sédimentologique et paléontologique, - une étude structurale à partir de données spatiales, géophysiques, et de terrain, - une étude thermochronologique (AFT), - et une étude interprétative sismique. Je propose ainsi une accrétion progressive et oblique de l'Amérique Centrale sur l'Amérique du Sud, s'initiant au sud de la région d'Istmina à partir de 40-37 Ma. La plaque Caraïbe, piégée entre l'arc volcanique et la marge continentale sud-américaine, disparaît progressivement sous l'Amérique du Sud. Vers 15 Ma, l'accrétion de l'arc dans la partie colombienne se termine. Au Panama, la convergence continentale se poursuit, mais le système s'inverse. Une nouvelle subduction s'initie : la plaque Caraïbe subducte sous l'isthme. Les déformations compressives engendrées par l'accrétion contrôlent la migration des masses sédimentaires et permettent la surrection progressive de l'isthme créant le pont inter-Amériques. / The Panama Isthmus is located on the SW boundary of the Caribbean plate, at the junction of the South American, Nazca and Cocos plates. The isthmus is composed of two island arcs forming Central America. It formed by a complex history of plate subductions. The major tectonic event in this region is attributed to the accretion of Central America with South America between 12 and 25 Ma. The aim of this thesis is to document the deformation before, during and after the accretionary continental process. The main purpose is to better understand how a volcanic arc collides against a continental margin in order to reconstruct the tectonic history of this region since 70 Ma until today. This thesis combines: - a sedimentological and paleontological studies, - a structural study from spatial, geophysical and field work data, - a thermochronological study (AFT), - and an interpretative seismic study. I propose the initiation of progressive and oblique arc-continent collision during 40-37 Ma. The Caribbean plate, trapped between the arc and the continent, progressively disappeared beneath the South American continent. Around 15 Ma, the Colombian part of Central America was accreted and the convergence of Panama toward the continent progressed and produced a new subduction zone whereby the Caribbean plate subducted beneath the Panama Isthmus. Compressive deformations, caused by the collision, still actively control the migration of sedimentary masses, allowing the progressive emergence of the isthmus and forming the inter-American land bridge.

L'oscillation de Madden-Julian (MJO) est la composante dominante de la variabilité intrasaisonnière dans l'atmosphère tropicale, se propageant vers l'est dans la bande équatoriale. Elle se compose d'un centre convectif (phase active) accompagné de la convergence des anomalies du vent zonal de bas niveau et de la divergence de niveau supérieur, et de zones de convection faible (phases supprimées). Trois périodes de l'activité MJO sur l'océan Indien et le continent maritime ont été choisies : 6-14 avril 2009, 23-30 novembre 2011 et 9-28 février 2013. Les simulations avec et sans paramétrisation de la convection ont été réalisées pour un grand domaine avec le modèle atmosphérique Méso-NH. Il a été obtenu que les simulations avec convection paramétrée n'étaient pas capables de reproduire un signal MJO. Pour 2009 et 2011, lorsque le couplage entre la convection et la circulation de grande échelle était fort, les simulations avec convection explicite ont montré une propagation visible de la MJO, ce qui n'a pas été le cas pour 2013. Pour 2011, les processus contribuant à la suppression de la convection ont été étudiés avec une analyse isentropique pour séparer les masses d'air ascendantes ayant une température potentielle équivalente élevée des masses d'air subsidentes ayant une température potentielle équivalente faible. Trois circulations de grande échelle ont été trouvées : une circulation troposphérique, une circulation de percées nuageuses dans la couche de tropopause tropicale, et une circulation de masses d'air à faible température potentielle équivalente dans la basse troposphère. Cette dernière correspond aux intrusions d'air sec de grande échelle des zones subtropicales dans la bande équatoriale, trouvées principalement pendant la phase supprimée de la MJO sur l'océan Indien. / The Madden-Julian Oscillation (MJO) is the dominant component of the intraseasonal variability in the tropical atmosphere, propagating eastward in the equatorial band. It consists of a convective center (active phase) accompanied by the low-level zonal wind anomaly convergence and the upper-level zonal wind anomaly divergence, and zones of weak convection (suppressed phases). Three time periods of the MJO activity over the Indian Ocean and the Maritime Continent were chosen: 6-14 April 2009, 23-30 November 2011, and 9-28 February 2013. The simulations with and without convective parameterizations were performed for a large domain with the atmospheric model Méso-NH. It was obtained that the simulations with parameterized convection were not able to reproduce an MJO signal. For 2009 and 2011 when the coupling between convection and large-scale circulation was strong, the convection-permitting simulations showed a visible MJO propagation, which was not the case for 2013. For the 2011 episode, the processes contributing to the suppression of the convection were studied using an isentropic analysis to separate the ascending air masses with high equivalent potential temperature from the subsiding air masses with low equivalent potential temperature. Three large-scale circulations were found: a tropospheric circulation, an overshoot circulation within the tropical tropopause layer, and a circulation of air masses with low equivalent potential temperature in the lower troposphere. The latter corresponds to the large-scale dry air intrusions from the subtropical zones into the equatorial band, mostly found during the suppressed MJO phase over the Indian Ocean.

Student Number: 0108593A - MA research report - School of Social and Sciences - Faculty of Humanities / South Africa’s diplomatic involvement in the continent and particularly in Cote d’Ivoire is the main focus of this paper. Therefore, the rationale of this dissertation is to investigate the reasons of the African Union (AU) to choose South Africa as a peace broker rather than the Cote d’Ivoire crisis as such. South Africa’s diplomatic engagement in Cote d’Ivoire in 2004 was as a result of numerous attempts by AU, Economic Community of West African States (ECOWAS) and France to find a peaceful solution to what was once the most economic and political stable country in West Africa. The crust of this paper is to ascertain reasons why the AU designated South Africa the responsibility to mediate a peace process in Cote d’Ivoire. Furthermore, What difference can South Africa really make in Cote d’Ivoire search for peace, given the failure of other third parties as well as South Africa’s ability to export its model of power-sharing in the continent. Against this backdrop, it is also vital to examine reasons why South Africa accepted to broker a peace deal in Cote d’Ivoire in November 2004 rather that two years ago when the conflict was on its early stages. In fact, this is not the first time South Africa was requested to help solve conflicts in West Africa. Interestingly, at first, South Africa refused to offer mediation in West Africa in 2003 citing reasons that it was overburdened in other peacekeeping missions in Africa. Thus, this paper will attempt to find reasons why this time around South Africa accepted the job to mediate a peace process in Cote d’Ivoire in the backyard of Nigeria.

Made available in DSpace on 2016-04-27T19:31:02Z (GMT). No. of bitstreams: 1 Jose Francisco dos Santos.pdf: 3253109 bytes, checksum: bd77bc157b8ef496b790f21e98dc6c87 (MD5) Previous issue date: 2015-01-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This research had as finality to reflect about the relation Brazil and Angola in the diplomatic, economic, social and cultural aspects, through a documentation of the Itamaraty and bibliography pertinent to the period between 1974 until the current days. We observed that the work is going to concentrate itself in the report produced by the Brazilian embassy in Lisbon, in the year of 1974, to the Brazilian Ministry of Exterior Relations regarding the Carnation Revolution and, mainly, the situation of the independence processes of the African countries, which, until that moment, were called Overseas Provinces . We registered in the following year the diplomatic documents produced mainly by the Brazilian Representation in Angola throughout the year of 1975, led by the diplomat Ovídeo de Andrade Melo. In a second moment, we analyzed the documents of the Itamaraty from 1976 until 1983. The other periods are covered by bibliography and depositions concerning the relation Brazil and Angola / pesquisa teve por finalidade refletir a respeito da relação Brasil e Angola nos aspectos diplomáticos, econômicos, sociais e culturais, por meio de documentação do Itamaraty e bibliografia pertinente ao período entre1974 até os dias atuais. Observamos que o trabalho irá concentrar-se no relatório produzido pela Embaixada brasileira em Lisboa, no ano de 1974 para o Ministério das Relações Exteriores do Brasil a respeito da Revolução dos Cravos e principalmente sobre a situação do processo de independências dos países africanos que até aquele momento eram chamadas de Províncias Ultramarinas . Registramos no ano posterior os documentos diplomáticos produzidos principalmente pela Representação Brasileira em Angola ao longo do no de 1975, liderado pelo o diplomata Ovídeo de Andrade Melo. Em um segundo momento, analisamos documentos do Itamaraty de 1976 até 1983. Os demais períodos são recobertos por bibliografia e depoimentos referentes a relação Brasil e Angola

Os métodos potenciais são conhecidos como uma ferramenta útil para estudos regionais. Na Ibéria Ocidental, a gravimetria e a magnetometria podem ser utilizadas para auxiliar no entendimento de algumas questões sobre a estruturação tectônica offshore. Nesta região, tanto as estruturas geradas pela quebra continental, quanto às herdadas do embasamento variscano, tem uma importante contribuição para a resposta geofísica regional observada com estes métodos. Este trabalho tem como objetivo correlacionar as feições geofísicas observadas com alguns modelos geológicos do arcabouço tectônico da Ibéria Ocidental já publicados na literatura. Mapas filtrados foram usados para auxiliar no reconhecimento de diferentes assinaturas geofísicas, os quais foram calculados a partir dos mapas de gravidade Bouguer e do campo magnético total tais como o gradiente horizontal total, derivada tilt, derivada vertical, e integral vertical. O domínio crustal continental foi definido a partir da interpretação dos dados gravimétricos, utilizando gradiente de gravidade horizontal total da Anomalia Bouguer. Os dados magnéticos, originais e filtrados, foram utilizados para identificar mais três domínios regionais offshore, que sugerem a existência de três tipos de crosta não-siálica. Dois deles são propostos como domínios de transição. A região da crosta de transição mais próxima do continente tem uma fraca resposta regional magnética, e a porção mais distal é um domínio de anomalia de alta amplitude, semelhante à resposta magnética oceânica. O limite crustal oceânico não pôde ser confirmado, mas um terceiro domínio offshore, a oeste da isócrona C34, poderia ser considerado como crosta oceânica, devido ao padrão magnético que apresenta. Alguns lineamentos do embasamento foram indicados na crosta continental offshore. As feições gravimétricas e magnéticas interpretadas coincidem, em termos de direção e posição, com zonas de sutura variscanas, mapeados em terra. Assim, esses contatos podem corresponder à continuação offshore destas feições paleozoicas, como o contato entre as zonas de Ossa Morena-Zona Centro-Ibérica. Nesta interpretação, sugere-se que a crosta continental offshore pode ser composta por unidades do Sudoeste da Península Ibérica. Isto permite considerar que a Falha de Porto-Tomar pertence a uma faixa de deformação strike-slip, onde parte das bacias mesozoicas da margem continental está localizada. / Potential field methods are known as a very useful tool to regional studies. On Western Iberia, gravimetric and magnetometric data could be helpful to understand some questions about the offshore tectonic framework. In this area, both continental break-up features and inherited continental basement structures have a strong contribution to compose the regional geophysical response on gravimetric and magnetometric maps. This work aims to correlate observed geophysical features of the Iberian margin with some geological models about the tectonic framework of Western Iberia, already published on literature. Filtered maps were used to recognize different geophysical signatures, which were computed from both calculated Bouguer gravity and total magnetic field, such as total horizontal gradient, tilt derivative, vertical derivative, and vertical integration. The continental crustal domain was defined from gravity data interpretation using an enhanced total horizontal gradient of Bouguer Anomaly maps. Magnetic data was used to identify three more regional offshore domains that could indicate three types of non-sialic crust. Two of them are proposed as transitional domains. The landward transitional crust has a very weak regional magnetic response, and the seaward one is a high amplitude anomaly domain, similar to oceanic magnetic response. The oceanic crustal boundary was not confirmed, but a third offshore domain, seaward from C34 isochron, could be considered as oceanic crust by its magnetic pattern. Some basement lineaments were indicated in the offshore continental crust. Gravimetric and magnetic features coincide in terms of their direction and position with Variscan suture zones mapped onshore. Therefore these contacts could correspond the offshore continuation of these Paleozoic features, such as the Ossa-Morena Zone and Centro-Ibérica Zone suture zone. In this interpretation, offshore continental crust could be formed by units from Southwest Iberia. It allows considering the Porto-Tomar fault as a part of a swath of strike-slip deformation, where mesozoic basins are located.

The Marathon PGM-Cu deposit is hosted by the Coldwell alkaline complex, which consists predominantly of gabbro and syenite and was emplaced at 1108 Ma as part of the Mid-Continent Rift System. Mineralization at the Marathon PGM-Cu deposit is hosted by the Two Duck Lake Gabbro (TDLG), a fresh olivine-bearing gabbro. The Marathon deposit contains several zones of mineralization including the Basal Zone, the Main Zone and the W-Horizon. The W-Horizon is a high-grade PGE zone characterized by low S, low Cu/Pd and high Cu/Ni. The sulphide mineral assemblage is predominantly chalcopyrite and bornite. This contrasts with the Main Zone where the dominant sulphide mineral assemblage is chalcopyrite and pyrrhotite. The Main Zone contains higher S, higher Cu/Pd and shows a decrease in Cu/Pd and pyrrhotite/chalcopyrite from base to top. Four drill holes were selected for detailed analysis to characterize the W-Horizon style of mineralization. Detailed petrographic study of the pristine and largely unaltered TDLG shows that wide spread hydrothermal alteration is not responsible for the mineralization. Detailed outcrop mapping shows that the TDLG intruded as a series of multiple intrusions in a dynamic magmatic system. Geochemical studies through the W-Horizon show that the mineralization is not the result of crystallization in a layered intrusion. The results of geochemical assays and electron microprobe analysis of olivine grains show that the chemistry through the TDLG hosting the W-Horizon is erratic. This data supports the TDLG intruding as a series of sills in a dynamic conduit environment. The calculated sulphide metal tenors for the W-Horizon are higher than can be explained by closed system R Factor models. Multistage dissolution upgrading in an open system is examined as the process forming the W-Horizon. This model is able to produce the sulphide metal tenors observed in the W-Horizon. Sulphur loss also affects grades and tenors and was examined through geochemical and petrological data. The change in sulphide mineral assemblage from a pyrrhotite and chalcopyrite (S-rich) to chalcopyrite and bornite (S-poor) supports S-loss. Whole rock S and Se contents are also analyzed to investigate S loss, a lower S/Se indicates that sulphur has been removed from the system. Average S/Se values are ~800 for the W-Horizon, ~1980 for the Main Zone and ~1700 in unmineralized samples. The very low S/Se observed within the W-Horizon supports S-loss. Sulphur loss in a dynamic magmatic conduit system is proposed for the formation of the W-Horizon mineralization. In this model sulphur undersaturated basaltic magma interacted with an immiscible sulphide liquid in a magma conduit, resulting in the dissolution of sulphide into the basaltic melt and PGE enrichment.

Understanding the cause of abrupt climate change in the geologic past can help assess the potential magnitude and variability of future changes in regional and global climate. The research presented here focuses on some of the first records of hydrologic variability in the central North American continent during an interval of Marine Isotope Stage 3 (24-57 thousand years before present (ka)). Sediment core MD02-2551 from the Orca Basin, northern Gulf of Mexico, is used to document the first detailed melting history of the southern margin of the Laurentide Ice Sheet (LIS) during MIS 3, and to record terrestrial inputs from the Mississippi River related to changes in evaporation-precipitation over the mid-continent, from 28-45 ka.Paired measurements of oxygen isotopes and Mg/Ca-SST on the planktonic foraminifera Globigerinoides ruber (pink) are used to calculate the oxygen isotopic composition of seawater and test one of the key hypotheses for abrupt climate change. Five rvals of freshwater input from 28-45 ka do not match the abrupt Dansgaard-Oeschger temperature oscillations recorded in Greenland ice. Rather, summer melting of the LIS may have occurred during Antarctic warming and likely contributed to sea-level variability during MIS 3. A detailed assessment over one of the meltwater events, using the oxygen and carbon isotopic composition of G. ruber and the deeper dwelling Neogloboquadrina dutertrei, demonstrate that meltwater was confined to the surface layers and likely had an impact on the biological pump in the Gulf of Mexico. A similar oxygen isotopic composition of seawater record determined from the year-round white G. ruber suggests that melting was not limited to the warmest summer months. The timing of LIS meltwater input is decoupled from an interval of enhanced wet conditions over the North American continent and increased Mississippi River discharge, as shown by a suite of organic and sedimentologic proxies. Increasing summer insolation on the orbital scale may have led to a northward migration of the Intertropical Convergence Zone and an intensification and westward shift in the conical position of the Bermuda High, which shuttles moisture to the North American continent and contributes to flooding in the Mississippi River drainage basin.

The Marathon PGM-Cu deposit is hosted by the Coldwell alkaline complex, which consists predominantly of gabbro and syenite and was emplaced at 1108 Ma as part of the Mid-Continent Rift System. Mineralization at the Marathon PGM-Cu deposit is hosted by the Two Duck Lake Gabbro (TDLG), a fresh olivine-bearing gabbro. The Marathon deposit contains several zones of mineralization including the Basal Zone, the Main Zone and the W-Horizon. The W-Horizon is a high-grade PGE zone characterized by low S, low Cu/Pd and high Cu/Ni. The sulphide mineral assemblage is predominantly chalcopyrite and bornite. This contrasts with the Main Zone where the dominant sulphide mineral assemblage is chalcopyrite and pyrrhotite. The Main Zone contains higher S, higher Cu/Pd and shows a decrease in Cu/Pd and pyrrhotite/chalcopyrite from base to top. Four drill holes were selected for detailed analysis to characterize the W-Horizon style of mineralization. Detailed petrographic study of the pristine and largely unaltered TDLG shows that wide spread hydrothermal alteration is not responsible for the mineralization. Detailed outcrop mapping shows that the TDLG intruded as a series of multiple intrusions in a dynamic magmatic system. Geochemical studies through the W-Horizon show that the mineralization is not the result of crystallization in a layered intrusion. The results of geochemical assays and electron microprobe analysis of olivine grains show that the chemistry through the TDLG hosting the W-Horizon is erratic. This data supports the TDLG intruding as a series of sills in a dynamic conduit environment. The calculated sulphide metal tenors for the W-Horizon are higher than can be explained by closed system R Factor models. Multistage dissolution upgrading in an open system is examined as the process forming the W-Horizon. This model is able to produce the sulphide metal tenors observed in the W-Horizon. Sulphur loss also affects grades and tenors and was examined through geochemical and petrological data. The change in sulphide mineral assemblage from a pyrrhotite and chalcopyrite (S-rich) to chalcopyrite and bornite (S-poor) supports S-loss. Whole rock S and Se contents are also analyzed to investigate S loss, a lower S/Se indicates that sulphur has been removed from the system. Average S/Se values are ~800 for the W-Horizon, ~1980 for the Main Zone and ~1700 in unmineralized samples. The very low S/Se observed within the W-Horizon supports S-loss. Sulphur loss in a dynamic magmatic conduit system is proposed for the formation of the W-Horizon mineralization. In this model sulphur undersaturated basaltic magma interacted with an immiscible sulphide liquid in a magma conduit, resulting in the dissolution of sulphide into the basaltic melt and PGE enrichment.

Thesis (doctoral)--Universität Bremen, 2005. / Includes bibliographical references (p. 113-125).